FROM THE TELEGRAPH OF 16 MAY 2006
The reticent heliocentrist
If we observe
the sky without being seduced by what passes for modern knowledge, it should be
clear to the meanest intelligence that all objects in the universe revolve around
the earth. They are pasted on an enveloping screen which keeps going round. Its
axis of rotation runs through the pole star. We see different parts of the
screen from different places on the earth. Those in India cannot see the
Southern Cross; those in Mauritius cannot see the Pole Star.
Well, that
cannot be quite right, for some objects change their positions with respect to
one another. The moon is particularly wayward. It runs faster than the others;
every thirty days it comes back to the position it started from.
And then, all
the objects sway around the equator; they amble north and south. In summer they
all move north, in winter south. A few are even more wayward. Some, such as
Mercury and Venus, race ahead for some time and then retrace their steps.
Others, such as Jupiter and Saturn, similarly accelerate and decelerate, but
over longer periods. These objects wander across the sky in a rather disorderly
way.
Aristotle
(384-322 BC), a student of Plato, systematized this picture. The earth was in
the middle of a shell – the firmament. Above the firmament were three circles
housing fire, which heated the earth, water, which rained on earth, and air,
which buffeted the earth with hurricanes. Beyond the three elements moved the
planets; the sun was the earth’s fourth planet, beyond the moon, Mercury and
Venus. Beyond them were the stars. They all moved in imperfect circles, like
ellipses.
Scholars who
followed Aristotle made observations of the movement of heavenly bodies and
tried to fit them to circular models, but there were discrepancies between the actual
and predicted movements. They made more sophisticated models, which are however
lost. Finally, Claudius Ptolemy (85-165), who lived in Roman Egypt, wrote a
huge mathematical text which has come down to us in the Latin translation of
the Arabic translation of the original Greek, called Almagest. His theory was
that all heavenly bodies went round the earth, but that the centre of rotation
– called the equant – was slightly displaced from the earth, so they came
closer to the earth sometimes and sometimes receded. And they themselves revolved
in small circles, called epicycles, around a point which revolved round the
earth. When even epicycles failed to fit observations, Ptolemy revolved points
in epicycles which themselves revolved around points going round in epicycles
around a point rotating round the earth. He kept adding epicycles until his
model came close to observations.
Ptolemy’s theory
survived for 1400 years. It reigned not just because it fitted facts, but
because it was consecrated in the Bible; the ninety-third Psalm said, “Thou
hast fixed the Earth immovable and firm, Thy throne firm from of old; for all
eternity Thou art God.” That settled all doubt. The church ruled people’s
hearts; the lands it owned and the tax it collected gave it control on their
livelihoods. So geocentricity was orthodoxy.
Then in 1489,
Lucas Watzenrode became bishop of Varmia, which was then in East Prussia; it is
now a part of Russia, which defeated Germany in World War II and displaced it westwards.
As was normal in that age, Watzenrode appointed his 16-year-old nephew Nicolaus
canon of his cathedral in Frauenburg. Nicolaus did not have to do much, but it
gave him income. So he took off for Italy. He studied law in Bologna and
medicine in Padua and, after seven years of perambulation, became doctor of canonic
law from Ferrara. Then he returned to his job, started collecting tithes from
tenant farmers of the church, and eventually set up home in the tower of the city’s
wall facing the Frauenburg cathedral.
From the 50-ft tower
Nicolaus had plenty of opportunity to watch stars. He started recording their
positions, and matching them to Ptolemy’s circles. On doing this, he found that
the point near the earth around which everything revolved was in the same place
as the sun. If he assumed that it was the sun, it enabled him to dispense with
many of Ptolemy’s epicycles.
Nicolaus was
faced with a dilemma. On the one hand he had made a fantastic discovery which
should have been publicized from the rooftop. On the other hand, what he now
believed went against the Bible, and could expose him to the charge of heresy. So
he chose to keep quiet. In any case, there were no journals of astronomy in his
time to publish his theory; and publishing a book would have been a mammoth
undertaking. Movable type printing had been invented only a century earlier –
Johannes Gutenberg had set the Bible to type only in 1455. There were few
printers; none of them was within a few hundred miles of him. Science was done
very differently in that age. A scholar gathered a few students around him and
lectured to them; students traveled from teacher to teacher to gather
knowledge. There were universities with libraries; but few other than dedicated
scholars collected books themselves. Those who did, treasured them; they read
them again and again, and made copious notes in their margins.
Then one scholar
in Wittenberg, Georg Joachim Rheticus, heard about the strange theories of
Nicolaus (I may as well reveal his last name – Copernicus), and decided to go
and learn about them from the horse’s mouth. He arrived in Frauenberg in 1538.
He found that
Copernicus had written up his theory in a huge tome full of observations and
mathematics (it started with the admonition: ‘Those who do not know geometry may
not enter here’). Fascinated by Copernicus’s heliocentric theory, he wrote off a
70-page introduction called Narratio
Prima (First Description), and got it printed in nearby Danzig. It was an
immediate sensation; next year it was reprinted in Basel. It took him two
years, but he finally persuaded Copernicus to let him take his manuscript for
publication by Petreius, a famous academic printer in Wittenberg. In 1543, it
was published under the title, Nicolai
Copernici Torinensis De Revolutionibus Orbium Coelestium Libri Sex (Six Books on the Revolutions
of the Heavenly Spheres by Nicolaus Copernicus of Torin).
Copernicus was
70 when De Revolutionibus was
published; he died soon after. Others became more famous for their heliocentric
views, particularly Galileo, because he was persecuted for heresy, and Kepler, because
of his three elegant laws. Arthur Koestler, in The Sleepwalkers, his popular 1959 book on early astronomers,
called Copernicus’s De Revolutionibus
the book nobody read. Incensed by that dismissal, Owen Gingerich, Research
Professor of Astronomy and History of Natural Sciences in Harvard, spent a
lifetime tracing all copies of De
Revolutionibus and finding out who had owned and read them. In the process,
he became an expert on the book, was often consulted by antiquarian book
dealers on the quality and provenance of copies they handled, and was called to
court as expert. He tells the story of his career in The Book Nobody Read: One Man’s Quest to Visit Every Surviving Copy of
One of the World’s Great Books (Arrow Books).
